Scientific Forecaster Discussion
fxus66 klox 220318
Area forecast discussion
National Weather Service Los Angeles/Oxnard California
818 PM PDT Thu Mar 21 2019
Scattered showers will wind down for most areas this evening, but
lingering showers are possible over the mountains until midnight.
Friday will be dry, but clouds will increase through the day as
another storm system approaches. Light rain and mountain snow will
be possible on Saturday. Below normal temperatures are expected
to continue through the weekend.
Short term (thu-sun)...21/818 PM.
Broad troughing over the state continues to move east this
evening. A few clouds and isolated shower activity remain over
the area, but a drying trend is starting to take shape as a ridge
of high pressure just off the California coast builds into the
region from the west. Warming will take place on Friday as the
ridge asserts itself over the region, but temperatures will still
remain below seasonal normals for this time of year.
Stratus clouds cannot be ruled out across the coastal and valley
areas as ridging aloft builds in over a moist layer near the
surface. The best chance of any stratus will be areas north of
Point Conception, but with the moist soils, patchy ground fog is
certainly possible. The least likely place to see any low clouds
and fog will be southern Santa Barbara County, where northerly
low-level flow will likely keep stratus out of the area. Locally
gusty winds could develop in the usual windy spots for northerly
winds, such as southern Santa Barbara County and through the
Interstate 5 corridor. These winds are not expected to become
No updates to the forecast are planned at this time.
***From previous discussion***
The next system will start pushing in early Saturday. This one
still seems to stay mostly north of pt Conception as most of the
energy will be deflected to the north due to the previous ridge.
But most areas will see plenty of clouds through the morning and
early afternoon hours before drier northwest flow kicks in. Rain
amounts for northern areas expected to be a quarter inch or less
in most areas but locally up to a half inch in the slo County
Dry and warmer Sunday with light offshore flow and weak ridging
Long term (mon-thu)...21/224 PM.
Another trough tries to push onshore Monday. The models are still
at odds as to how far south the moisture will reach with the European model (ecmwf)
still favoring the ridge and keeping everything north. There are
enough ensemble solutions to at least go with a chance of rain for
northern areas Monday and Monday night but dry conditions expected
south of pt Conception.
Models follow that up with another trough late Tue/Wed. Here again
best chances northern areas but this one has a better chance of
reaching la County, especially if the latest European model (ecmwf) is correct. A
vast majority of GFS ensembles keep it dry at least for la County
but certainly Worth a chance of rain at this point given the
Thursday looks dry for now but enough variations in the ensembles
to keep a slight chance of rain going for now until there's a
better model consensus.
At 2300z, there was no marine layer or inversion at klax.
Moderate confidence in VFR scattered-bkn050 through 02-03z, with MVFR
bkn025 with any -shra that occurs. After 03z, moderate confidence
in VFR conditions through the remainder of the period. There is a
20 percent chance of MVFR cigs for coastal sites, and a 10
percent chance of IFR/LIFR fog/br around 12z Friday, with the
highest chance at kprb.
Klax...moderate confidence in the 00z taf. 30% chance that vcsh
conditions persist 1-2 hrs past 03z. Moderate confidence in VFR
conditions through the period, except for a few hours of MVFR cigs
Kbur...moderate confidence in the 00z taf. 30% chance of MVFR
conditions in vcsh through 05z. Moderate confidence in VFR
conditions through the period, except 30% chance of MVFR
cigs/vsby between 12-17z.
Winds have diminished below Small Craft Advisory levels this evening. There is a
decent chance that west to northwest winds will increase to
Small Craft Advisory (sca) strength Fri afternoon and evening,
especially beyond 20 miles from the coast. These winds will also
generate choppy seas on top of the long period west to northwest
swell. Northwest winds will increase some on Saturday with Small Craft Advisory
likely off the central coast, and a large long period northwest
swell building in. Small Craft Advisory level seas are possible across the
northern outer waters sun into Sun night. Otherwise, Small Craft Advisory conds
are not expected sun thru Tue.
Pz...Small Craft Advisory in effect until 9 PM PDT this evening
for zones 650-655-676. (See laxmwwlox).
Hazard potential outlook (sun-thu).
High surf and dangerous rip currents are expected over the